Which component is commonly found in laptops to help adjust brightness?

The component commonly found in laptops to help adjust brightness is the ambient light sensor. This sensor automatically detects the lighting conditions in the surrounding environment and adjusts the screen brightness accordingly to improve visibility and reduce eye strain. By adapting to natural light changes, it enhances the user experience by providing optimal screen brightness without the need for manual adjustments.

Optical drives, USB ports, and SD card slots serve different functions related to data storage and connectivity but do not play a role in adjusting screen brightness. Thus, the ambient light sensor is essential for managing screen brightness automatically, making it the correct answer.